Vesicoureteral Reflux (VUR)

By
Ronald Rabinowitz, MD, Professor of Urology and Pediatrics, University of Rochester Medical Center;Jimena Cubillos, MD, Associate Professor of Clinical Urology and Pediatrics, University of Rochester School of Medicine and Dentistry

Vesicoureteral reflux is retrograde passage of urine from the bladder back into the ureter and sometimes also into the renal collecting system, depending on severity.

Etiology

Vesicoureteral reflux (VUR) is most often due to congenital anomalous development of the ureterovesical junction. Incomplete development of the intramural ureteral tunnel causes failure of the normal flap valve mechanism at the ureterovesical junction that permits reflux of bladder urine into the ureter and renal pelvis. Reflux can occur even when the tunnel is ordinarily sufficient if bladder pressure increases due to bladder outlet obstruction or dysfunctional voiding. Dysfunctional voiding includes infrequent voiding, constipation, or both, which may prolong resolution of VUR.

Pathophysiology

Reflux of urine from the bladder into the ureter may damage the upper urinary tract by bacterial infection and occasionally by increased hydrostatic pressure. Bacteria in the lower urinary tract can easily be transmitted by reflux to the upper tract, leading to recurrent parenchymal infection with potential scarring. Renal scarring can eventually cause hypertension and sometimes renal dysfunction. VUR is a common cause of UTI in children; about 30 to 40% of infants and toddlers with UTI have VUR.

Symptoms and Signs

Children typically present with a history of fetal hydronephrosis or with a UTI or appear as part of a sibling screening. Rarely, children present with hypertension, which is more commonly a long-term consequence of renal scarring. Children with UTI may have fever, abdominal or flank pain, dysuria, frequency, urgency, wetting accidents, or rarely hematuria.

Diagnosis

Ultrasonography

Voiding cystourethrography (VCUG)

Sometimes radioisotope scan

Urinalysis and culture are done to detect infection. In infants and young children, a catheterized specimen is usually required.

Evaluation includes ultrasonography of the kidneys, ureters, and bladder before and after voiding, and then fluoroscopic VCUG. Renal ultrasonography is used to evaluate kidneys for size, hydronephrosis, and scarring. VCUG is used to diagnose VUR and to evaluate for other bladder abnormalities. A radioisotope cystogram (radionuclide cystography) may be used to monitor reflux. Renal cortical involvement with acute infection or scarring is best diagnosed with succimer (dimercaptosuccinic acid) nuclear scans when indicated. Urodynamic studies, when appropriate, may show elevated intravesical pressure.

Reflux findings on VCUG are graded on a scale from I to V (see Table: Grades of Vesicoureteral Reflux*). The degree of reflux can be affected by bladder capacity and bladder dynamics.

Mild: Grades I and II

Moderate: Grade III

Severe: Grades IV and V

Grades of Vesicoureteral Reflux*

Grade

Characteristics

I

Only the ureters are involved, but not the renal pelvis.

II

Reflux reaches the renal pelvis, but the calyces are not dilated.

III

The ureter and renal pelvis are dilated, with minimal or no blunting of calyces.

IV

Dilation increases, and the sharp angle of the calyceal fornices is obliterated.

V

The ureter, pelvis, and calices are grossly dilated.

Papillary impressions frequently are absent.

*As defined by the International Reflux Study Committee.

Treatment

Sometimes antibiotic prophylaxis

Sometimes injection of a bulking agent or ureteral reimplantation

Mild to moderate vesicoureteral reflux often resolves spontaneously over months to several years. It is very important to keep children free of infection. Previously, children with mild to moderate VUR were given daily antibacterial prophylaxis, but there is currently no consensus on this practice. Most pediatric urologists recommend antibiotics for severe VUR at all ages and for VUR grades II to V in children < 2 yr. However, the American Academy of Pediatrics does not recommend prophylaxis for children with VUR grades I to IV after the first febrile UTI. There are multiple age- and weight-based recommendations for antibiotics, but, typically, children are given trimethoprim/sulfamethoxazole at bedtime, nitrofurantoin at dinnertime, or cephalexin twice daily.

Severe vesicoureteral reflux accompanied by high intravesical pressures is treated with anticholinergic drugs (eg, oxybutynin, solifenacin succinate) and rarely surgery (such as botulinum toxin or bladder augmentation). Patients with bowel and bladder dysfunction benefit from behavioral modification with or without biofeedback.

Monitoring

History, physical examination (including BP measurement), laboratory testing with urinalysis and serum creatinine, and imaging using VCUG and ultrasonography are done at regular intervals depending on the child's age and the severity of the reflux and associated complications. Typically, children < 2 yr have ultrasonography every 4 to 6 mo (more frequently in children with significant nephropathy visible on ultrasonography); older children have ultrasonography every 6 to 12 mo. VCUGs are repeated every 1 to 2 yr (longer intervals for higher grade VUR, bilateral VUR, and/or older children).

In addition, toilet-trained children should be assessed at each visit for constipation and infrequent voiding, incontinence, urinary urgency, and nocturnal enuresis, which are common signs of elimination dysfunction, and treated as needed with behavioral modification and/or drug therapy.

Key Points

VUR is most often due to congenital anomalous development of the ureterovesical junction.

Reflux of urine from the bladder into the ureter may cause bacterial infection of the upper urinary tract; about 30 to 40% of infants and toddlers with UTI have VUR.

Diagnose by using VCUG.

Monitor by using serial ultrasonography and VCUGs.

Mild to moderate VUR often resolves spontaneously, but more serious disease may require surgical intervention.

Children with newly diagnosed VUR are given prophylactic antibiotics depending on their clinical course.

Assess toilet-trained children for dysfunctional elimination and treat them appropriately.

Last full review/revision November 2016 by Ronald Rabinowitz, MD; Jimena Cubillos, MD

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